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Member postings for Andy48

Here is a list of all the postings Andy48 has made in our forums. Click on a thread name to jump to the thread.

Thread: Is there a new breed of servo ?
11/03/2020 16:19:56
Posted by Nigel R on 11/03/2020 12:19:13:

so, to be clear, the corona servos, they have weak lugs that easily snap, and they can burn out when used with a "normal travel range" because they only support 45 deg rotation either side of centre?

Ideally you should not take a servo beyond 30 degrees either side of centre, because of the geometry.

11/03/2020 16:18:23
Posted by Tim Ballinger on 11/03/2020 12:42:48:

Gary,

Thanks for that information on servo testers and the potentially adverse interaction with servo travel limits.

I’ve never felt the need for a servo tester so I may be missing out but on the other hand I may have saved some grief should I have used one for reliability/ endurance testing .

Tim

I always use a servo tester when installing servos in models. I use a digital one, set to the mid-point for setting up, and always test full throw for my transmitter in either direction. This is usually more than accurate enough to maiden will very little trim needed.

11/03/2020 11:23:12

A really sensible and informative post. Cheers Gary.

10/03/2020 14:38:14
Posted by Tim Ballinger on 09/03/2020 15:36:27:

While compiling my spreadsheet of likely solutions I eventually found a current consumption quoted . It was for the Corona DS919MG - a 12g servo in the class I am looking for albeit the Torque at 1.7 is a little low compared to others. However the quoted current consumption is 200 -240 mA.
So at 4 servos all waggling its only around 1A which is well within scope of most SBEC or esc/SBEC combinations. I am therefore going to assume all in this class will be similar.

Tim

Is that torque really low? 1.7 -presumably kg.cm means the servo would stall when a load of 1.7kg is placed 1cm from the centre of the arm. Most of my servos only have a maximum distance of 1.5cm throw, so they will clearly handle 1kg. 1kg is probably more than enough to rip a servo arm out of an aileron or rudder on a normal sized sports plane for instance. Indeed it would probably rip the whole aileron out of the wing.

While I have never actually tried calculating it, I suspect the force on an aileron/elevator or rudder on a sports plane going at full wack is far lower than the above figures.

09/03/2020 12:29:03
Posted by Tim Ballinger on 09/03/2020 10:24:17:

Thanks for all the input I shall definitely be going with sub £10 mini ( 9-17g) digital ; just not sure what make yet.

Tim

There is a lot of value in choosing carefully first. Having standardised some time ago on a particular size and make, I bought a few packs of spare arms from Banggood for a song. Turned out each pack was actually 5 packs. Now I have a whole tray full!

As you will be aware, another point in favour of standardising is that each different type of servo has a completely different fitting for the servo arm.

Thread: Proxxon FET 2070 table saw: I tested It!
09/03/2020 12:24:39

Got one of these. Brilliant bit of kit, cuts plywood superbly. Can't begin to guess how much I've saved by cutting my own balsa stripwood.

Just horribly expensive to buy in the first place.

Thread: Is there a new breed of servo ?
08/03/2020 18:57:04
Posted by Tim Ballinger on 08/03/2020 17:18:51:

Interesting you mention Emax servos Andy, I was looking at those on one web Site ( one I consider reputable) and see they have replaced the mini (17g) Analogue Emax with one of their own branded Mini digitals .

Not sure whether that implies equality or superiority but thanks for the Emax endorsement.

Tim

Yes I noticed that on the same website, as I was looking for slightly larger 17g ones, only because that size fits an ARTF I was thinking of getting. That size Emax have never been that common.

One thing I do like about the 11g Emax ES08MD/ES08MA series is the way the corner where the lead goes in is angled, so the servo can be slotted into a tight fitting servo box.

08/03/2020 16:02:43

I try and use the same servos in each model. I standardised on Emax 11g ones, and so far they have been superb, and no failures. Most of my models fall into the 2-4kg sports model category and are electric, a good point as noted by Erflog. The weight saving is really significant. 4 standard servos at 44g = 176g. 4 11g servos = 44g.

A few basic rules:

1. I always buy metal geared servos.

2. Always use individual servos for each aileron.

3. I use straight pushrods wherever possible, and avoid snakes to keep friction low.I ten to use carbon fibre tubes with 2mm wire glued in each end.

4. Avoid the Chinese fakes. Even on £4 Emax servos, they are everywhere. Now I only get them from a reputable dealer.

Thread: Isolating A Lipo.
08/03/2020 11:28:04
Posted by ron evans on 07/03/2020 19:38:40:

Fully agree, fuse is a no no.

I'm sure I read somewhere that modern speed controllers are much more tolerant of battery lead extensions.

I've used quite long extensions -up to 30cm without adverse effect on a 5S 5000mAh system, and all my models have the leads extended to some extent. Never blown an ESC yet.

I think this is one of those things which may have been true years ago but is now consigned to the backet of old wives' tales.

Edited By Andy48 on 08/03/2020 11:30:26

07/03/2020 16:57:26
Posted by Dai Fledermaus on 07/03/2020 15:47:18:

I seem to remember reading about a removable blade type fuse, as used in cars, to isolate the battery, but the details escape me. It might have been in a old copy of RCM&E.

This used to be BMFA's solution, but it is horrible for 2 reasons. Firstly spade fuses are not meant to be removed repeatedly, and secondly what happens if the fuse blows?

Much simpler, glue an XT60 into a strongish part of the fuselage with epoxy. Much neater than the wall plate and very robust.

Thread: DH Tiger Moth 1400mm
07/03/2020 11:22:30

Wow! A good old Farnell power supply still going strong. It was 50 years ago I left their factory.

Thread: On board volt & amp meter
06/03/2020 16:00:17

Use a wattmeter. Much simpler. It will give you the current consumption.

Thread: Sd card update
06/03/2020 15:59:05

Avoid the synchronisation SD card! It is not immediately clear exactly what is happening there, and you can lose files.

The way you did it before is the best way. Copy the SD card contents to your computer, update the SD card, and then copy the sound files back plus any other files you keep on the SD card such as firmware updates and model pictures.

Thread: Individual cell voltage of LiPo flight battery.
05/03/2020 18:24:07
Posted by Gordon Whitehead 1 on 05/03/2020 17:36:13:

As a matter of interest, now that all cell voltages in a pack can be readily measured and logged, how much excess voltage depression compared with the rest of the cells in a pack makes a cell qualify as failed enough to make the pack unusable? Or do all the cells generally degrade at the same rate with a small random spread in full power terminal voltage so that whilst one cell will hit the warning voltage first, the others are pretty close anyway so that they can all be considered as failing together?

Is there any noticeable correlation between excess voltage drop at full power, say 12C for a 5000 pack, and capacity loss?

Gordon

Its not that easy because I measure the cells when under dynamic load, i.e. full power, and its generally one cell that shows up quite a lot more, though there is very little difference when measured under no load conditions. At the end of the day every battery is different.

Once one cell has gone you can be sure the rest will be not far behind.

04/03/2020 17:03:03
Posted by Gordon Whitehead 1 on 01/03/2020 20:43:24:

Reading the references quickly, it looks to me as if the Unilog is a data logger intended for post-flight evaluation of the measurements. Unless it can report in real time and sound a warning when Peter's 3.3V threshold has been reached, it seems to me to be of doubtful utility unless you are a data collecting enthusiast. Does the Frsky system announce when an individual cell has breached a chosen lower limit?

Gordon

Following on from Bob's comments, I use the FrSky battery sensors on all my models. I only have a couple as they swap from model to model with ease. Yes it does warn in real time.

I use them to warn when an individual cell reaches the lower limit I set when setting up a model. The sole purpose for this is to warn when a battery pack is failing, because when I get the warning message when taking off on full power with a freshly charged battery, I know one cell is failing. Measurements on the ground normally don't show up anything, but its a different matter when the battery is under full load.

 

Edited By Andy48 on 04/03/2020 17:03:51

Thread: X10 Horus update
24/01/2020 20:19:31

See here:

**LINK**

24/01/2020 17:11:33
Posted by Andy Joyce on 24/01/2020 16:35:46:

Probably correct but did wonder if opentx offers any improved functions WRT the FRSky OS.

OpenTX is far far better IMO, once you get used to the way it works. Remember FrOS is based on OpenTX and uses the basic terminology started by OpenTX.

Edited By Andy48 on 24/01/2020 17:11:50

Thread: SWEET & SMART Acronyms meaning??
23/01/2020 16:41:46
Posted by kc on 23/01/2020 10:17:48:

Andy said " Model selected is correct - Automatic these days with binding" ---that's not correct with all TX ! With Spektrum perhaps but not Futaba etc. There is no Model Match with my Futaba 2.4 so it's possible to use the wrong memory.

Edited By kc on 23/01/2020 10:18:13

Oh gosh! Futaba are behind the times! Spektrum has it, FrSky has it, why not Futaba?

Thread: Capacity checker accuracy?
22/01/2020 21:09:14

I've used a couple of such battery checkers and frankly they have ended up in the bin as next to worthless. All they can do is measure the voltage. Now I use a current sensor and this give a very accurate reading of the capacity, and invariably matches the reading on the battery charger.

Thread: SWEET & SMART Acronyms meaning??
22/01/2020 20:09:34
Posted by Christopher Morris 2 on 21/01/2020 10:34:22:

Be S.M.A.R.T. with your transmitter.

S .... Switch on

M .... Model selected is correct / Meter in the Green

A .... Aerial secure / extended

R .... Rate switches all in correct positions

T ..... Transmitter voltage good and Trims all in correct positions

Bit of a laugh these days really.

S Switch on. Yeah nothing happens until you do.

M Model selected is correct - Automatic these days with binding. Meter in the green. - No meter, voltage reading instead.

A Areal secure / extended. Internal aerial thus nothing to do.

R Rate switches all in correct position. Get audible warning if any of the switches/sliders are not. Correct positions set when programming model. These days we need to consider more than just rate switches too. What about an arming switch for electric for instance?

T Transmitter voltage good. Erm yes checked that under "M". Trims all in correct position. Obviously, with digital trims the positions are stored with the model memory.

Verdict, not very smart at all. Needs a bit of updating to come into the 21st century, I've no intention of going back to use old style 35Mhz transmitters.

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